Add the avocado halves to a medium mixing bowl. Squeeze lime juice over the avocados and toss gently to coat. Add the cumin. Lightly mash the avocados with a fork, keeping them chunky.
Fold in the chopped jalapeño, cilantro, pomegranate arils, and a pinch of salt. Stir in the crumbled feta cheese, if using. Taste and adjust seasoning with more salt if needed.
Heat about an inch of oil in a medium skillet over medium heat until hot.
Fry the plantain slices for 2-3 minutes per side until lightly golden. Remove from oil and drain on paper towels.
Transfer the fried plantain slices to a cutting board. Using the back of a wooden spoon, smash them down into flat, round disks.
Return the smashed plantains to the hot oil and fry for another 2-3 minutes on each side until golden brown and crispy. Remove to a paper towel-lined plate and sprinkle with chili salt (if desired). Enjoy immediately!